The polymerase chain reaction (PCR) is commonly used in genetics research and manufacturing for many purposes, such as reproducing and increasing tiny DNA samples into a sample large enough for analysis. The PCR process may involve numerous cycles of a thermal cycling process to obtain the multiplicative effect, which may cause the process to extend over a long time period, resulting in increased cost and decreased number of possible situations in which the PCR may be useful.
One common present method of performing a PCR process is to take the sample, for example a DNA sample from a crime scene, place the sample in a test tube with a liquid material useful for PCR reactions and testing, and move the test tube sequentially into different temperature controlled water baths. This method may result in long cycle times due to the repeated physical motion of the test tube from one bath to another, liquids dripping from the test tubes during temperature bath switches, and increased cost due to operator employment cost or automated equipment cost.
Another method of performing a PCR process may involve placing the sample into liquid material useful for PCR reactions in a test tube and inserting the test tube into holes in an otherwise solid thermal block. The thermal block is then heated and cooled to desired temperatures in cycles necessary for the PCR to take place. This method may result in long cycle times due to the thermal inertia of the thermal block material and increased operation costs due to the power consumption associated with repeatedly heating and cooling the thermal block.
Another method of performing a PCR process may involve placing the sample into a liquid material useful for PCR reactions and testing and injecting the liquid into a long narrow sinuous channel in a thermal material layer. Applying a gaseous or liquid pressure to move the liquid sample down the sinuous narrow channel at a selected rate from one temperature area into a different temperature area and back again may result in the PCR process experiencing the desired temperature changes without the lost time, mess and cost consequent to the previously mentioned methods. This narrow sinuous channel method may experience problems with accurate temperature ranges since the two or more areas having the selected temperatures are in thermal contact with each other through the thermal material, which may result in the PCR reaction occurring at temperatures that are not exactly at the desired temperature, and may result in PCR variations from one process run to another, with the consequent loss of repeatability. This method may also suffer from potential contamination issues with the PCR material remaining on the narrow channel walls as the main mass of PCR material is moved from location to location, which may also result in inconsistent results. The accuracy of motion of the PCR material in the narrow sinuous channel may not be visible inside the thermal material, which may result in the main mass of the PCR material not being in the proper location for the correct temperature at the right time, again resulting in reduced repeatability and inconsistent results.